Geek Trivia

Scratch and sniff technology has popped up in all sorts of odd places over the years, but by far, one of the stranger places is scent-impregnated video game discs. It wouldn’t be the first time that video games and scratch and sniff technology crossed paths, however. Back in 1995, the official player’s guide packaged with the Super Nintendo game EarthBound included a set of scratch and sniff cards, some of which were rather putrid. And that certainly wasn’t the last time scratch and sniff technology would mesh with video gaming either.

In 1999, as part of a rather bizarre marketing ploy, Sony released Gran Turismo 2 with a scratch and sniff disc. The original game came as a two-disc set, and it was claimed that the second disc in the set, a blue and white disc with extra game content, had a “real racing pit smell”. When scratched by curious gamers, the disc released the scent of burnt rubber.

Following the release of a scratch and sniff disc in 1999 by Sony, Electronic Arts apparently didn’t want to miss the scratch and sniff train and released their own scratch and sniff game disc. FIFA 2001, an incarnation of the popular soccer series, included a scratch and sniff disc that, when scratched, released the scent of stadium grass. Apparently, the smell of burnt rubber and grass was enough to satisfy people; no scratch and sniff games have been released since then—although Katy Perry released her 2010 Teenage Dream album (the Deluxe Edition) with a cotton candy scented scratch and sniff CD.

For those of you who have been wondering exactly how scratch and sniff technology works, it’s a rather interesting bit of chemistry and industrial engineering all rolled into one. Back in the 1960s, an organic chemist working for 3M, Gale Matson, created a micro-encapsulation process intended to facilitate the production of copies without carbon paper. 3M’s marketing department, in an effort to get more bang for their buck out of the recent invention, came up with several alternatives for the technology including the preservation and distribution of scents.

The actual process of creating scratch and sniff material is more complicated than you’d imagine. Most people assume that the scent is simply painted onto the surface, but that would yield a scent that didn’t last very long since the scented oil would evaporate over time. To create scratch and sniff stickers, scientists cook up an oil mixture that smells like they want it to (i.e. candy, fresh cut grass, or even less pleasant smells like body odors and rotting garbage). They mix the scented oil into a vat with a solution of water and water-soluble polymer, then they blend the mixture until the oil has separated into millions of tiny drops (20-30 microns wide), and finally, they dump in a chemical catalyst. The chemical catalyst causes the polymer to encapsulate the tiny drops of oil. After a few steps to refine, wash, and dry the capsules, the final product is a pile of tiny, tiny scent beads.

The beads are placed into a tank and mixed with a water base and an adhesive, forming a thick slurry, which is then ready to be applied to surfaces. When the user scratches the surface, the friction of their finger breaks the microcapsules and the scent is released. It is because of this encapsulation process that old, but unscratched scratch and sniff stickers can still smell fresh even after years in storage—the scented oil is safely stored away in the polymer shell waiting for someone to drag their finger across the surface and say “Ugh, why would anyone make Scratch ‘N Sniff Garbage Pail Kids?”